The invention relates to a self-inking hand stamp of claim 1.
From U.S. Pat. No. 5,152,223 A, e.g., a self-inking hand stamp is known in which the lateral parts of an actuator yoke on their inner side have integrally molded bearing blocks guided in slit-type openings in the side walls of the housing, and in which lateral parts there are provided cylindrical bearing recesses which house and rotatably accommodate pin-shaped axle portions integrally molded with the stamp plate of the hand stamp. These axle portions thus define the turning axis of the stamp plate about which the stamp plate is turned by 180° during actuation of the hand stamp, when the actuator yoke is pressed downwards relative to the housing. What is disadvantageous there is that during mounting, the lateral parts of the actuator yoke must be moved apart under elastic deformation until the stamp plate engages with its axle portions in the cylindrical bearing recesses. By this, the material of the actuator yoke is subjected to wear, so that a corresponding elastic, yet solid synthetic material must be chosen, wherein it may happen nevertheless that the lateral parts of the actuator yoke will break during mounting or dismounting of the stamp plate. Here, it is a further disadvantage that the actuator yoke must be locked relative to the housing by insertion of locking parts through openings above the ink pad, e.g. for withdrawing the ink pad from its associated insertion compartment and refilling of stamping ink. This type of locking additionally complicates handling of that hand stamp.
A simpler form of locking the actuator yoke on the housing of the hand stamp in various positions is disclosed in U.S. Pat. No. 5,727,467 A: In the hand stamp known from this publication, resilient snap-in tongues comprising latching hooks are provided on the lateral parts of the actuator yoke, which can be latched in or hooked in corresponding latching recesses on the side walls of the housing of the hand stamp by pushing the former inwards. On the stamp housing, two latching recesses are provided one above the other, thereby defining two locking positions, i.e. an upper one for withdrawing or inserting the ink pad, and a lower one, in which the hand stamp has its smallest vertical dimension and in which the stamp plate with its printing characters is oriented downwards so that, in this position, also printing characters may be exchanged if the stamp plate or the stamp unit is appropriately designed. Yet, also here it holds that essential parts of the lateral parts of the actuator yoke are elastically deformed during locking, resulting in great material wear over extended periods of time, which may lead to fatigue symptoms and which can be counteracted only by appropriately choosing a synthetic material of high quality. It would, however, be desirable to be able to use also less expensive synthetic materials.
Furthermore, from DE 19 06 426 B (and, similarly, from U.S. Pat. No. 5,058,501 A), self-inking stamps are known in which a respective turning or control axle passes through the respective stamp unit, and with each end region thereof passes through a control slit in the stamp housing, wherein the end region of the axle is mounted in the associated lateral part of the actuator yoke by means of a slipped-on bearing bushing part, and is axially secured by means of a safety part formed, e.g., by an outer annular flange on the bearing bushing part. These stamp constructions involve comparatively much effort during their production as well as, in particular, when assembling the individual stamp parts.
From U.S. Pat. No. 6,067,905 A, or from the corresponding WO 99/16624, respectively, a structure of a hand stamp of the same type as the present hand stamp is known, in which a separate inverting axle passes through a stamp plate, this inverting axle being mounted in the ends of the lateral parts of the actuator yoke and secured there by means of separate safety elements each. For this purpose, the inverting axle includes peripheral grooves at its ends which cooperate with corresponding bearing projections in bearing seats of the lateral parts of the actuator yoke, and the separate safety elements press the inverting axle to these bearing projections. The main function of these safety elements is to secure, by their secure mounting on the respective lateral part of the actuator yoke, the inverting axle in axial direction so that the inverting axle cannot unintentionally move in axial direction or even inadvertently fall out of the stamp unit.